Optical window for an intracorporeal device

ABSTRACT

Optical windows for intracorporeal devices, intracorporeal devices comprising a window and a method for forming a window for an intracorporeal device are provided. The method comprises placing within a mold an assembly comprising a mandrel located within a pair of parts separated by a collar of window material, heating the window preform effective to cause the window material to soften, and applying force to urge together the pair of parts to deform the window material so as to form a window. The intracorporeal devices, such as imaging devices, include guidewires, catheters, endoscopes. In addition, the method is suitable for joining plastic parts to other parts, such as metal and ceramic parts.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of co-pending parent application havingU.S. Ser. No. 10/025,334, filed Dec. 18, 2001, the contents of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to methods and apparatus formanufacturing an optical window for an intracorporeal device thatprovides functional access to a body lumen, and to methods for joiningparts together. In particular, the invention is directed to methods andapparatus for making an optical window for an imaging guidewire,catheter, or endoscope.

BACKGROUND OF THE INVENTION

Intracorporeal devices are devices suitable for introduction into apatient's body, for example, into a body lumen of a patient. Manyclinical procedures require the insertion of wires, tubes, probes orother objects into a body lumen of a patient. For example, guidewiresand catheters may be used for gaining access to the coronaryvasculature, as in an angiogram or in angioplasty. A guidewire is athin, flexible device used to provide a guiding rail to a desiredlocation within the vasculature (or other body cavity) of a patient. Aballoon catheter is a device with an interior lumen with at least aportion of the catheter being able to expand. In coronary angioplasty, aballoon catheter, guided by a guidewire, is positioned within apartially-occluded coronary artery where its balloon portion is expandedin order to press against and enlarge the lumen of a blood vessel inwhich it is situated. Alternatively, endoscopy requires the introductionof an endoscope into the lumen of a patient, as may be done during acolonoscopy.

The ability to decide where to locate a catheter during a clinicalprocedure can be improved by providing interior images of the bodylumen, such as the blood vessels during angioplasty or the colon duringcolonoscopy. It is often critical to the success of an angioplastyprocedure that a balloon catheter be properly located within a bloodvessel. Thus, imaging by guidewire, catheter, or other such device canbe of great importance to the success of the procedure.

Imaging endoscopes, guidewires and catheters have been described, as inU.S. Pat. Nos. 5,321,501 and 5,459,570 to Swanson et al., and U.S. Pat.No. 6,134,003 to Tearney et al. Catheters adapted for optical imagingusing non-visible light may be useful as well, as disclosed in U.S. Pat.No. 5,935,075 to Casscells et al. Such imaging devices typically use anoptical fiber to carry light. All patents, supra and infra, are herebyincorporated by reference in their entirety.

It is often advantageous to have a window in an imaging catheter,imaging guidewire, endoscope, or other imaging probe to allow opticalaccess between the exterior of the device and the optical fiber or lightpath within the device. U.S. Pat. No. 6,134,003 to Tearney et al.discloses a rigid plastic clear window, or using three or more metal orplastic metering rods to connect two parts of a guidewire across awindow. However, the choice of material and the method of constructionof the window is critical to the success of the device. A window made ofbrittle material may break and shatter if it fails, leading to thedispersion of broken window shards within a body lumen if such failureoccurs during a clinical procedure. Such materials are thus unacceptablein devices designed for use within a body lumen. A non-brittle, plasticmaterial does not have the disadvantages of a brittle window material.

However, a suitable connection between the window material and othercomponents of an intracorporeal imaging device is required. For use inan intracorporeal imaging device such as a guidewire, catheter, orendoscope, the window must be attached to proximal and distal portionsof the intracorporeal imaging device.

Conventional techniques for forming and attaching windows have beenfound to be difficult and unsuccessful. Use of rods to connect two partsof a guidewire or other intracorporeal imaging device across a windowblocks visual access and interferes with the imaging function of awindow. The extremely small dimensions of the window components makesconventional molding, extrusion molding, injection molding and insertmolding processes difficult and costly to use in making a window forthese intracorporeal devices, and such methods only provide a lowlikelihood of success.

For example, the small outer diameter of a guidewire makes it extremelydifficult to use conventional methods to successfully press fit anextruded window over the formed guidewire mating ends. Conventionalattempts to expand or drill out the inner diameter of the window tubingto obtain a fit present problems with alignment, obtaining tooling andmaintaining low enough tolerances to make a good bond of either desiredtype. Further, if one were to use conventional techniques and to expandthe extruded window to allow a fit over the ends of the guidewire, somewindow material would assume a larger than desired outer diameter, whichwould have to be cleanly removed by some other operation. Additionally,the tolerances associated with extrusion (typically +/−0.001″) wouldrequire that the average cross-sectional area of the window wall besignificantly lower than the maximum cross-section possible within itsdimensional constraints, so that, with prior art methods, the strengthand utility of the window could be impaired.

Conventional methods for bonding the ends of the window with an adhesiveso as to mate appropriately with the proximal and distal portions of aguidewire or catheter suffer from similar disadvantages as otherconventional methods. Conventional molding processes force a meltedplastic into a mold cavity where it rapidly cools. In order to form atubular window a mold pin must be placed inside the mold to leave ahollow interior. However, with such conventional techniques, whileforcing melted plastic into a mold, at least a portion of the meltedplastic would cool significantly while flowing into the mold.Conventional techniques would then require that the plastic be forcedvery rapidly into the cavity under high pressures to fill the cavitybefore cooling in an attempt to avoid this problem. However, such rapid,high pressure flow would damage or warp the mold pin forming the innerdiameter of the window. This is due to the length of the window innerdiameter that is required to ensure that the fiber optic assembly can bereliably aligned such that the light exits the window in all bend,temperature and assembly conditions.

Attempting to balance the molding forces by having more than one plasticentrance into the mold requires a more complex and expensive mold. Thismethod suffers from disadvantages due to the low volume of plastic inthe window, and the uncertainty involved in timing the plastic flow'sentry into the cavity. Additionally, molds and equipment of this typeare very expensive.

Accordingly, there is need in the art for methods for forming a windowfor an imaging guidewire, catheter or endoscope.

SUMMARY OF THE INVENTION

The present invention is directed to methods for forming windows and forjoining materials. In some embodiments, the invention is directed tomethods for forming a window for an intracorporeal device, windowsformed by the novel methods, and intracorporeal devices comprising awindow formed by the methods, The novel methods may be used to formoptical windows for guidewires, catheters, endoscopes, and otherintracorporeal devices useful for accessing a body lumen. For example,the optical window formed by the methods of the invention may comprise asmooth translucent or transparent tube comprising a portion of animaging guidewire. The methods can be used to form or mold into placevery small plastic parts, especially those that require tight tolerancesand a small inner diameter of a relatively long length Thus, in someembodiments, the methods of the invention are effective to join plasticparts, in particular very small plastic parts, with other parts, such asmetal or ceramic parts, to form joints and junctions. Devices andmethods utilizing the methods of the present invention are disclosed inco-owned application Ser. No. 10/024,986, “Optical Guidewire HavingWindows or Apertures” to Jalisi et al.; application Ser. No. 10/025,515,“Rotatable Ferrules and Interfaces for Use with an Optical Guidewire,”to Webler et al.; and application Ser. No. 10/025,149, “Sheath forGuiding Imaging Instruments,” to Webler et al., all of which are filedconcurrently herewith, and the disclosures of which are all herebyincorporated by reference in their entirety.

An optical window formed by the methods of the invention may include asmooth translucent or transparent tube that is attached to distal andproximal portions of an imaging guidewire, an imaging catheter, animaging endoscope, or other device suitable for accessing a body lumen.By way of example, the methods will be illustrated with a description ofthe formation of a window for an imaging guidewire. However, it will beunderstood that the methods may also be used to form windows forcatheters, endoscopes, and any other intracorporeal device useful foraccessing a body lumen.

The invention includes methods for forming a window for anintracorporeal device, comprising placing an assembly with a windowpreform at least partially within a mold, softening the window preform,and applying force. In some embodiments, softening the window preformmay be accomplished by heating the window preform. The assembly includesa proximal tubular member, a distal member, a window preform, and amandrel. A window preform is disposed between the proximal tubularmember and the distal member. A window preform may flow when desired,and may be made, at least in part, of a material that softens when itstemperature is raised. The softened window preform material may bedeformed onto proximal and distal portions of an intracorporeal device,which portions may be configured so as to contact, engage or grip thewindow perform or formed window. The assembly has a longitudinal axis,and the mandrel is disposed along the longitudinal axis at leastpartially within the proximal tubular member, the window preform, andthe distal member. The step of raising the temperature of the windowpreform may be effective to soften the window preform. The step ofapplying force is effective to urge together the proximal tubular memberand the distal member, and is effective to deform the window preform soas to form a window or to join separate parts together. In otherembodiments, the window preform is made, at least in part, of a materialthat hardens upon warming, exposure to light, or other treatment.

Heating the window preform may be effected, for example, by at least onemethod selected from the group consisting of induction heating,conduction heating, infra-red radiation, ultrasonic heating, frictionheating, hot air heating, and allowing the preform temperature to riseto ambient temperature.

In some embodiments of the methods for forming a window for anintracorporeal device, the mandrel protrudes from an end of theassembly, or, in further embodiments of the methods, the mandrelprotrudes from each end of the assembly. The mandrel may have a polisheddistal end, may be coated with a coating such as a lubricious coating,lined with a lining such as a lubricious lining, and may be polishedand/or treated, for example, to have a smooth or a lubricious surface.Any lubricious coating, such as a coating of a fluoropolymer (e.g.,Teflon), titanium nitride, or other coating known in the art, may beused in the practice of the novel methods.

The invention also provides methods for joining a plastic part with atubular member. Such methods include placing at least partially within amold an assembly comprising a tubular member, a mandrel and a plasticpreform that softens when heated; softening the plastic preform; andapplying force effective to urge together the tubular member and theplastic preform effective to deform the plastic preform and to join theplastic preform to the tubular member. In some embodiments, the plasticpreform may be softened by heating.

The mold may be comprised of a suitable material or combination ofmaterials having a higher melt temperature than the window material,such as metal, plastic, ceramic, glass, and combinations of thesematerials. In some embodiments of the methods, the mold comprisesborosilicate glass. The mold may be coated on one or more surfaces witha coating such as a lubricious coating, lined on one or more surfaceswith a lining such as a lubricious lining, and may be polished and/ortreated on one or more surfaces, for example, to have a smooth or alubricious surface. Any lubricious coating may be used in the practiceof the novel methods.

Optical radiation may be useful in imaging and optical sensing. Windowmaterials comprise translucent materials (i.e., materials capable oftransmitting optical radiation such as light), including materials whichmay be transparent (i.e., translucent materials capable of transmittingan image). The terms “light” and “optical radiation” are used herein tomean electromagnetic radiation including but not limited to visiblelight, infrared radiation, ultraviolet radiation, and other radiation.Optical radiation may include radiation having a wavelength in the rangeof between about 0.1 to about 3 micron, and may particularly includeradiation having a wavelength between about 0 75 micron to about 2.5micron, or radiation having a wavelength between about 0.1 micron toabout 1 micron.

It is preferred that the window absorb, reflect or scatter as littlelight as possible. The windows of the present invention are very thin,so that light will pass through most polymers, resins, and othermaterials suited for such windows, without excessive attenuation. Lightis reflected at boundaries at which the index of refractance changes.Such light reflectance at each surface (both inner and outer surfaces)may be a major source of loss of light entering the window. Such lossesdue to reflectance at interface boundaries may be reduced or eliminatedby using materials with indices of refraction similar to that of thematerial adjacent the interface. Thus, losses due to reflectance at theouter interface boundary may be reduced or eliminated by using materialswith indices of refractance similar to that of the blood or plasma thatwill surround the window during use. For this reason, a windowcomprising a polymer or resin with an index of refraction between 1.3 to1.4, preferably very near to 1.34 will have reduced or negligible lossesdue to reflectance at the outer window interface. Similarly, filling thespace between the fiber-optic assembly and the inner face of the window(where the window's index of refraction is matched to blood or plasma)with saline or other solution with an index of refractance similar toblood or plasma, losses at the inner window surface would also bereduced.

Inventions embodying features of the invention include windows formed bythe methods, and intracorporeal devices including windows formed by themethods. Such intracorporeal devices may include an imaging device, suchas an imaging guidewire, an imaging catheter, an imaging endoscope, orother imaging device In addition, inventions embodying features of theinvention include combinations of objects and materials joined by themethods of the invention.

The novel methods disclosed herein avoid problems associated withconventional methods. Instead of press fitting an extruded window overformed guidewire ends to cause undesired expansion of the extrudedwindow, the novel methods of the invention provide for deformation of awindow preform softened by an increase in temperature, effective to forma window that is dimensioned within desired tolerances and without theneed for excess window material that must be cleanly removed by someother operation. The methods of the present invention avoid problems ofimproper flow speed and of too-rapid cooling within the mold by theplacement of the window preform in position within the mold beforeapplication of heat to soften it, so that no rapid flowing of meltedplastic occurs, and there is no problem of cooling during flow of meltedplastic.

Thus the present novel methods provide advantages over prior arttechniques in overcoming these and other problems with conventionaltechniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a longitudinal cross-sectional view of components of animaging device embodying features of the invention, prior to insertioninto a mold for manufacture of a window.

FIG. 1 B is a transverse cross-sectional view of the guidewirecomponents of FIG. 1A taken along line 1B-1B.

FIG. 1C is a transverse cross-sectional view of the guidewire componentsof FIG. 1A taken along line 1C-1C.

FIG. 2A is a longitudinal cross-sectional view of components of animaging guidewire and mold embodying features of the invention at thestart of the heat application step of a method of the invention.

FIG. 2B is a transverse cross-sectional view of the imaging guidewireand mold components as illustrated in FIG. 2A, taken along line 2B-2B.

FIG. 2C is a transverse cross-sectional view of the imaging guidewireand mold components as illustrated in FIG. 2A, taken along line 2C-2C.

FIG. 3A is a longitudinal cross-sectional view of components of animaging guidewire and mold embodying features of the invention after theheat application step of a method of the invention.

FIG. 3B is a transverse cross-sectional views of the guidewire and moldcomponents as illustrated in FIG. 3A, taken along line 3B-3B.

FIG. 3C is a transverse cross-sectional view of the guidewire and moldcomponents as illustrated in FIG. 3A, taken along line 3C-3C.

FIG. 4A, showing an optical imaging guidewire with a formed window, is alongitudinal cross-sectional view of an imaging guidewire embodyingfeatures of the invention following removal of the finished assemblyfrom the mold and removal of the mandrel.

FIG. 4B is a transverse cross-sectional view of the optical imagingguidewire of Fig. A, taken along line 4B-4B.

FIG. 4C is a transverse cross-sectional view of the optical imagingguidewire of FIG. 4A, taken along line 4C-4C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1A, 1B and 1C illustrate an assembly 10 embodying features of theinvention comprising a proximal tubular member 12 with a distal section14, a window preform 16, a distal member 18 with a proximal section 20,and a mandrel 22 with a distal section 24. As is illustrated in thelongitudinal cross-section of the assembly shown in FIG. 1A the assemblycomponents are arranged substantially along longitudinal axis 26.Viewing components of the assembly 10 illustrated in FIG. 1A in orderfrom left to right, mandrel 22 is disposed along longitudinal axis 26and extends through and closely fits into the inner diameters ofproximal tubular member 12 window preform 16 and distal member 18.Distal section 24 of mandrel 22 may be polished to a smooth surfacefinish in order to facilitate removal of mandrel 22 after formation of awindow.

Proximal tubular member 12 is the guidewire component proximal to thewindow preform 16, with distal section 14 of the proximal tubular member12 being adjacent window preform 16 and being configured to interfacewith the material of window preform 16 in a desired manner. Analogously,distal member 18 is the guidewire component distal to the window preform16, distal member 18 containing a proximal section 20 that is adjacentto and configured to contact and interface with the material of windowpreform 16 in a desired manner. Distal member 18 may have a bore ordepression configured to receive a mandrel 22, or may have a flat orcurved face configured to contact a mandrel 22. In some embodiments ofthe invention; distal member 18 does not contact mandrel 22. In yetother embodiments, where the desire is to form a joint between aproximal tubular member 12 and a preform 16, there need be no distalmember 18 at all. It will be understood that the pieces of the assembly;although tightly fitting, are slidably engaged and may be moved relativeto one another The pieces of the assembly may initially be in contacteach other, although some or all the pieces of the assembly mayinitially not be in contact with other pieces of the assembly. With theapplication of force, proximal tubular member 12; window preform 16 anddistal member 18 are able to move along mandrel 22 so as to decrease orincrease the separation between window preform 16 and members 12 arid18. In FIG. 1, distal member 18 is shown with a depression configured toreceive mandrel 22; it will be understood that in some embodiments ofthe invention, distal member 18 may have a bore configured to receivemandrel 22; or alternatively may comprise a flat face configured tocontact window preform 16 and/or mandrel 22.

Distal section 14 of the proximal tubular member 12 and proximal section20 of the distal member 18 comprise the window attachment areas. Asillustrated in the Figures, the window attachment areas compriseportions of members 12 and 18 with reduced outer diameters, formingsteps upon which material from window preform 16 may flow and attach. Itwill be understood that in some embodiments of the invention, one orboth of window attachment areas 14 and 20 may include a portion orportions having increased inner diameter and unchanged outer diameterwith respect to the remainder of members 12 and 18, forming ledges underwhich material from window preform 16 may flow and attach. The desiredmanner of interface with the material of window preform 16 is such thatthese sections provide a strong interface between the proximal tubularmember and the window, and between the distal member and the window.Sections 14 and 20 may be roughened, grooved, provided with holes,provided with slots, provided with protrusions, treated or coated toimprove adhesion of window materials, provided with an irregularsurface, or in other ways known to those of ordinary skill in the artprepared and adapted to provide for a sturdy mechanical interface withthe window. For example, treatments that may be applied to distalsection 14 and proximal section 18 include application of a thin coatingof PRIMACOR™ (Dow Plastics, Midland, Mich.), a thermoplastic adhesive,to improve the adhesion of nylon windows.

Referring now to FIGS. 2A, 2B and 2C, the assembly 10 illustrated inFIG. 1 is shown inserted into a mold 28 illustrating features of theinvention. The mold 28 is shown in a cut away view in the longitudinalcross-section of the assembly shown in FIG. 2A. Preferably, mold 28 isconfigured to have a smooth circular inner diameter, especially in theregion where the window will be formed. The inner diameter of mold 28forms the outer diameter of the formed window. It is preferred that theother diameter of the formed window be as smooth and dimensionallyconsistent as practical for optical reasons. The inner diameter of mold28 is preferably sized to fit closely to portions of distal member 18and proximal tubular member 12. Gap 34 within the mold 28 comprisesthose areas not blocked by mandrel 22, proximal tubular member 12,distal member 18, and distal and proximal sections 14 and 20. Gap 34allows room for the flow of softened window material, and may optionallysurround one or more of distal section 14, proximal section 20, andwindow preform 16.

The arrows 30 and 32 show the directions of forces applied to proximaltubular member 12 arid distal member 18, respectively, during or afterthe time when the temperature of the window preform is raised, to urgeproximal tubular member 12 and distal member 18 together, creatingpressure in the softened material of window preform 16 effective tocause the window preform material to deform and to fill in gap 34 withinthe mold 28. Proximal tubular member 12 or distal member 18, or both,may move under the influence of the applied forces.

Mold 28 preferably has a smooth circular inner diameter and comprises amaterial having a higher melt temperature than the melt temperature ofwindow material 16. Mold 28 may be made of metal, plastic, glass,ceramic, polymer, or combinations of materials.

The longitudinal cross-section of the assembly shown in FIG. 3A and thetransverse cross-sections of the assembly shown in FIGS. 3B and 3Cillustrate the assembly 10 and mold 28 after the temperature of thewindow preform has been raised, as by, for example, the application ofheat, and the cooling of the mold 28. FIG. 3 illustrates a formed window36, formed by the application of heat and force (as shown by arrows 30and 32 in FIG. 2), after window preform 16 softened and/or melted,deformed (flowed) and then cooled. Note that gap 34 is not present atthis step of the method, window material 16 having deformed so as tofill gap 34 and so to create the formed window 36 illustrated in FIG. 3.The size, shape and finish of the outer surface of formed window 36 isdetermined by the inner surface of mold 28; similarly, the size, shapeand finish of the inner surface of formed window 36 is determined by theouter surface of mandrel 22. In the example illustrated in the Figures,proximal tubular member 12 is shown to have moved under the influence offorce 30.

FIGS. 4A, 4B and 4C illustrate the assembly 10 after it has been removedfrom the mold 28 and the mandrel 22 has been removed from the assembly10. The outer surfaces of proximal tubular member 12, formed window 36,and distal member 18 form a smooth continuous surface suitable for awindow for an intracorporeal imaging device such as a guidewire,catheter, or endoscope. The removal of the mandrel 22 provides a bore 38extending through the interior of proximal tubular member 12, formedwindow 36 and at least partially into distal member 18 (illustrated inFIG. 4A as extending into proximal section 20 of distal member 18). Afiber optic assembly 40 comprising an optical fiber and optical devicesincluding a mirror and a lens, is illustrated located within bore 38extending to the end 42 of the guidewire.

If the desired design configuration is the forming of a window alone, onone end and/or the other; as previously described, then proximal tubularmember 12 and/or distal member 18 must be removed to complete theprocess.

It will be understood that proximal tubular member 12 may not be theentire proximal portion of the guidewire body. It may be only a sectionof it and/or only a component used to join the final window assemblyproximally to the guidewire or guidewire assembly. Distal section 14 ofproximal tubular member 12 may be configured to interface with thewindow material of window preform 16 in a desired manner. Whereformation of the window alone is desired (for example, where it is notdesired to join components to other proximal components), then thedistal section 14 of proximal tubular member 12 may be configured toform the proximal end of the window in the desired configuration at thecompletion of the process. In such a case, distal section 14 may bedesigned or coated to release from the window material of window preform16. Because mold release agents may interfere with the subsequentbonding and/or press fit of the window to a proximally mating section ofthe guidewire or guidewire assembly, distal section 14 is adapted forease of release. In some embodiments of the method, in order to achievethis release of distal section 14 from window material of window preform16, distal section 14 may be polished, permanently coated tapered, or acombination of these. If the method is used for forming the windowalone, or for joining a plastic part to another part without joining toother components, mandrel 22 and proximal tubular member 12 may bepermanently joined or made in one piece. It will be understood that inthe methods of joining a plastic part to a tubular member, the terms“window perform” and “window preform 16” may be used to denote theplastic part that is joined to the tubular member.

It will also be understood that distal member 18 may not be the entiredistal portion of the guidewire. It may be only a section of it and/oronly a component used to join the final window assembly distally to theguidewire or guidewire assembly. If it is not desired to join to otherproximal components, that is, if forming of the window alone is desired,then the proximal section 20 of distal member 18 may be configured toform the distal end of the window in the desired configuration at thecompletion of the process. In this case, proximal section 20 is designedor coated to release from the window material. A method to achieve thisrelease is to polish, permanently coat and/or taper proximal section 20appropriately, which is preferred to the use of mold release agents,because mold release agents may interfere with the subsequent bondingand/or press fit of the window to the distally mating section of theguidewire or guidewire assembly. If forming the window alone, mandrel 22and distal member 18 may be permanently joined or made in one piece, butonly if mandrel 22 arid proximal lobular member 12 are not permanentlyjoined or made in one piece.

It will further be understood that distal section 14, or proximalsection 20, or both, may assume various configurations and includefeatures such as holes, grooves, channels, protrusions, and otherfeatures known in the art that may engage or interface with the windowmaterial of window preform 16 at the end of the process. Thus it will beunderstood that distal section 14, or proximal section 20, or both, maybe configured so as to contact, engage, or grip window preform 16 or theformed window 36 (shown in FIGS. 3 and 4) in a manner that provides amechanical lock to proximal tubular member 12 and distal member 18.

Mold 28 is made of a material with a higher melt temperature than thematerial comprising the window preform, and may comprise metal, plastic,glass ceramic, polymer, or combinations of materials. A preciselydimensioned inner diameter of mold 28 may be formed by machiningincluding electronic discharge machining (EDM), polishing, molding,casting, or other methods. For example, a piece of glass tubing may becast, blown, formed around a mandrel, or otherwise formed to have aprecisely formed inner diameter, to create a mold 28 suitable for thepractice of the method. In some embodiments of the methods of theinvention, mold 28 is constructed from borosilicate glass tubing.Another method for forming a mold 28 is to place a piece of heat shrinktubing over a jig, such as a mandrel of the desired size adapted formanufacture of mold 28, and to shrink a length of its center over thisjig. This jig is preferably precision ground and polished, so that theinner diameter of the shrunken portion of the heat shrink tubing will bevery smooth and precisely dimensioned when the jig is removed. Removalof the jig may be effected simply by pulling it in a longitudinaldirection out of the mold 28. Such removal may be aided by tapping themold or jig before pulling the jig, or by brief application of heat.Alternatively, the mold 28 may be made in a clam shell configuration andopened to insert and/or remove the assembly 10 from the mold 28.However, it will be understood that such a configuration might result ina parting line being formed on the window which would interfere withlight transmission.

Heat shrink tubing may be formed with a fluoropolymer (such as TEFLON®,which is polytetrafluoroethylene, or PTFE), fluorinated ethylenepropylene (FEP), or other materials. The diameter of heat shrink tubingis reduced by heating the tubing above a temperature, termed the shrinktemperature, that is determined by the make-up and manufacture of theheat shrink tubing. It is preferred that where heat shrink tubing isused, the window preform material has a softening/melting temperaturethat is below the shrink temperature so as to avoid further shrinkage ofthe heat shrink tubing during formation of the window or joint.

Mold 28 is illustrated in FIG. 2A as having a single inner diameterdimension; however, it will be appreciated that if distal member 18 andproximal tubular member 12 have different outer diameters, then mold 28may be formed to closely fit these outer diameters. In some embodimentswhere distal member 18 and proximal tubular member 12 have differentouter diameters, mold 28 is formed to closely fit these outer diametersin the regions that border sections 20 and 14, respectively. In thiscase, the assembly 10 may only be inserted or removed from the largerinner diameter section of the mold 28 and the assembly 10's (or eitherproximal tubular member 12's or distal member 18's) position relative tothe mold 28 must preferably be controlled so that the outer diameter ofthe window has the desired value. It will also be understood that theouter diameter of the formed window need not necessarily be as smooth aspossible around the interface areas distal section 14 and proximalsection 20 since these regions do not form an optical surface in thecompleted window.

To reduce possible loss of optical radiation or degradation of imagespassed through windows, smooth surfaces and matching of the index ofrefraction of the window with adjacent material (such as, e.g., blood orother body fluid) may be used. Complex strategies to match the indicesof refractance may be employed to reduce losses due to reflectance atwindow boundaries. Such complex strategies include, but are not limitedto, interposing between the fiber optic assembly and the window fluids(such as silicon oils) or coatings of a solid material having an indexof refraction intermediate between the indices of refraction of thefiber optic assembly arid the window, or intermediate to the index ofrefraction of the fiber optic assembly, the window and the externalmedium. Optionally, a coating having a thickness of ¼ the wavelength(based on the center frequency of the light to be transmitted throughthe window) may be used to reduce losses due to reflectance.

In addition, window materials may further include additives, such asglass particles or fibers, as may be included to alter the strength,flexibility, or other properties of the window. Such additives may alterthe optical properties of the window as well, by absorbing, reflectingor refracting light passing through the window. It is preferred that anyadditives have a refractive index similar or identical to the refractiveindex of the window material, which is preferably similar to that ofblood or plasma, in order to reduce any deleterious optical effects ofthe additives. Where such additives are included, it is preferred thatthe size, number, and concentrations of such additives be controlled inorder that any light scattering, light refraction, light absorption, orlight reflection that may result from the additives be limited toacceptable levels.

The window preform may include a material or a combination of materialsthat soften as the temperature is raised. The window preform may be madewith any suitable material which may deform under the desiredconditions, including suitable plastic or resinous materials. Plasticsthat soften as their temperature is raised, including polymericmaterials or polymer blends, are suitable materials for window preformsof the invention. Alternatively, window preforms may include resins,including epoxy resins, that have been cooled or frozen, and soften ormelt as the temperature of the cooled or frozen preform is raised as itwarms to ambient temperature. In addition, window preforms may includematerials that change their physical properties or change state inresponse to light, such as a resin or resin system that responds toultravoiolet, visible, or infra red light. Under a variety ofconditions, such as heating, mixing, or under exposure to light, resinsor resin systems “cure” (become polymerized). Window preforms comprisingresins are preferably uncured (not substantially polymerized) orpartially uncured (incompletely polymerized); thus, in preferredembodiments of window preforms comprising resins, the resins are atleast partially uncured.

In some embodiments of the invention, the plastic preform may comprise acombination of plastic materials, a resin that is at least partiallyuncured, a combination of resins at least some of which are at leastpartially uncured, and other materials and combinations of materials.Thus, the window preform may include a material selected from the groupconsisting of acrylic, polycarbonate, nylon, TEFLON®, polyethyleneterephthalate (PET), tensilized PET, resins, and blends thereof. Resinsused in a window preform may be at least partially uncured. Preferredwindow materials have high moduli of elasticity. Although materials suchas glass, fused silica and MgF₂ can be stronger and have higher flexuralmoduli than plastics, they are brittle and shatter when they fail. Sucha failure mechanism is not tolerable in a guidewire or other device foruse within a body lumen. Plastics can deform more without generatingfailure forces and their failure mechanism is to permanently deform,often significantly, prior to breaking, making them more suitable foruse in devices for accessing body lumens than more brittle materials.

In some embodiments of the invention, the plastic preform may comprise acombination of plastic materials, a resin that is at least partiallyuncured, a combination of resins at least some of which are at leastpartially uncured, and other materials and combinations of materials.Thus, the window preform may include a material selected from the groupconsisting of acrylic, polycarbonate, nylon, TEFLON®, polyethyleneterephthalate (PET), tensilized PET, resins, and blends thereof. Resinsused in a window preform may be at least partially uncured. Preferredwindow materials have high moduli of elasticity. Although materials suchas glass, fused silica and MgF₂ can be stronger and have higher flexuralmoduli than plastics, they are brittle and shatter when they fail. Sucha failure mechanism is not tolerable in a guidewire or other device foruse within a body lumen. Plastics can deform more without generatingfailure forces and their failure mechanism is to permanently deform,often significantly, prior to breaking, making them more suitable foruse in devices for accessing body lumens than more brittle materials.

In some embodiments of the method, mold 28 is heated effective toachieve a temperature hot enough to soften (which may include melting)the window preform 16, but not hot enough to degrade or burn the windowmaterial. For example, mold 28 may be heated sufficiently to soften thewindow material 16 effective to allow window material 16 to deform asdesired, e.g., when under pressure. As used herein, “deform” means toalter the shape of an object by pressure, stress, or heat, and“deformation” is the alteration of the shape of an object by pressure,stress, or heat. Deformation may include flow, as of an object that hasmelted.

Softening or melting that is effective to allow window material 16 todeform may be due to a change in viscosity of the material, or may bedue to a phase change in the material. Some plastic materials, includingsome materials of which window preform 16 is preferably comprised, havea material conversion temperature at which the state of the materialshifts from amorphous to liquid. In addition, some materials, such aslight-sensitive resins and resin systems, may be induced to change statebetween amorphous and liquid states by exposure to light or otherradiation. The mechanical properties of a material may be altered duringa change in viscosity or a phase change. In particular, during a changein viscosity or a phase change from amorphous to liquid, the flow of aplastic material may not be controlled. In order to avoid potentialproblems presented by these situations, in some embodiments of themethods, the temperature is controlled during the molding process sothat the material conversion temperature of the material of windowpreform 16 is not exceeded. In addition, in some embodiments of themethods, exposure to radiation is controlled during the molding processto control the mechanical and physical properties of the material ofwindow preform 16.

In some embodiments of the method, the window preform includes a frozenresin, such as a frozen epoxy resin mixture, that melts and softenswithin the mold as it returns to ambient temperature. In suchembodiments of the method, no external heat is required to effect thesoftening of the window preform. In addition, some resins and resinsystems are light-sensitive, so that the physical properties or physicalstate of the resins and resin systems change upon illumination by light.Window preforms including such resins or resin systems may be placedwithin a translucent or transparent mold to form mold assemblies thatallow the resins to receive appropriate wavelengths of light. Such moldassemblies may be used in the methods and systems of the invention toform windows or joints using light instead of, or in conjunction with,heat, to effect the softening of the window preform. In someembodiments, the resins or resins systems may harden upon illumination.

In some embodiments of the method, heating is performed whereby thetemperature is controlled to effect the desired deformation withoutdamage to window preform 16 and without adversely affecting its opticaland mechanical properties. The heat or heating energy used to soften ormelt the window preform 16 may be applied any number of ways, includingbut not limited to induction heating, conduction heating, infra-redheating, hot air heating, ultrasonic heating, friction heating, andother heating methods known to those of ordinary skill in the art. Insome embodiments of the methods, temperature controlled hot air (i.e.convection heating) is applied as a method of heating the windowpreform. The temperature of hot air used for hot air heating may be in arange of between about 200° F. and about 800° F., preferably in a rangeof between about 300° F. to about 500° F.

The methods of the present invention allow for the continuous control oftemperature and force (e.g., forces 30 and 32 illustrated in FIG. 2A)during formation of the window, and so allow for the continuous controlof the movement of proximal tubular member 12 and distal member 18. Thisprovides the advantage that the window preform 16 may be caused to flowslowly and then to cool slowly at much lower pressures (or sequences ofpressures) than are required for other molding processes. In this way,with the present invention, there can be considerably lower internalstresses in the window and in its attachments than are provided by othermolding processes. These lower internal stresses make the polymer windowstronger, and make its attachments to the proximal tubular member 12 anddistal member 18 stronger. The lower pressures of the molding processare also desirable because they help to prevent undesired loss ofmaterial (“flash”), by allowing for the control or elimination ofmaterial flow into gaps between the mandrel and proximal tubular member12 and distal member 18 or between the mold and proximal tubular member12 and distal member 18.

It will be understood by those of ordinary skill in the art that anysupporting structures used to hold the components of assembly 10 and toapply forces 30 and 32 to the components must allow for relativemovement between proximal tubular member 12 and distal member 18 underthe application of these forces. However, it will be understood that insome embodiments of the methods, one, or both tubular members 12 and 18may move substantially under the influence of the forces illustrated byarrows 30 and 32.

In some embodiments of the invention, window preform 16 is a piece of anextruded tube of the desired window material, with its outer diameterthe same or just less than the ultimate outer diameter of the completedwindow to be formed by the process. In other embodiments, the innerdiameter of window preform 16 is slightly greater than the outerdiameter of the distal section 24 of mandrel 22 so as to allow insertionof at least a portion of the mandrel 22 into the window preform 16. Thevolume of window preform 16 is preferably chosen to be the desiredvolume of the desired final window material configuration. It will beunderstood that, where window preform 16 comprises a tube ofsubstantially constant wall thickness, the volume of window preform 16is substantially determined by the length of window preform 16. If theprocess produces flash, that is, if window material may be lost duringthe process, as may occur, for example, by flow of window material intoundesired gaps between the assembled components, then additional windowmaterial may be provided, as by increasing the length of window preform16 to compensate for material expected to be lost.

In order to avoid the formation of bubbles in the windows, materialscontaining volatile additives and materials that degrade during heatingare not used, or used only sparingly, in window preforms. Wherematerials presenting risk of bubble formation are used, bubbles may beavoided by preferentially heating one end of the preform during windowformation, to cause plastic flow in the window preform so that bubblesor voids do not form. Any air present that may be present in any smallgaps while putting the assembly together prior to heating will be pushedout by the flow wave front.

The window preform may have any suitable length, for example a length ofbetween about 1 mm and about 11 mm. In some embodiments of the methodsof forming a window, the window preform has a length of between about 2mm and about 6 mm, preferably between about 3 mm and about 5 mm. Windowsformed by the methods of the invention may have any suitable length, forexample, a window formed by the methods of the invention may have alength of between about 0.3 mm and about 10 mm. In some embodiments, awindow may have a length of between about 1 mm and about 5 mm,preferably between about 2 mm and about 4 mm.

Windows formed by the methods of the invention may be of any suitablesize, for example windows formed by the methods may comprise annuli withan inner diameter of between about 0.001 inch and about 0.02 inch and anoutside diameter of between about 0.005 inch and about 0.05 inch. Insome embodiments of the methods, windows formed by the methods compriseannuli with an inner diameter of about 0.0075 inch or smaller and anoutside diameter of about 0.014 inch or smaller.

It will be appreciated that the greater the cross-sectional area of thewindow the stronger the window area. Maximum strength is desired forsafety reasons. In addition, mandrels are routinely precision ground totolerances of +/−0.0002 inch or less. Thus the inner diameter of a mold28 (which defines the outer diameter of window 36) and the outerdiameter of a mandrel 22 (which defines the inner diameter of window 36)can be tightly controlled to provide desired dimensions within tighttolerances. Thus an advantage of the present methods is that theyprovide windows of greater cross sectional area within desiredsmoothness and dimensional tolerances.

Fiber optic assembly 40 may comprise any assembly or system suitable foruse in an imaging system, and may comprise components and devices forimaging in the optical, infra-red, or any suitable wavelength. Imagingmay be by means of scanning, including confocal means, or other imagingmethods known in the art. It will be understood that guidewire end 42may comprise any guidewire end suitable for an intracorporeal device,and preferably comprises an optical interface effective to transmitoptical signals carried by fiber optic assembly 42.

The methods of the present invention solve the problems of bonding,maintenance of tolerances, high cost, and low probability of successassociated with prior methods. Mandrels, glass molds, heat shrink tubing(such as FEP, PTFE and other polymers, which may be used, e.g., to formmolds in some embodiments of the invention) and hot air sources arerelatively inexpensive. Because the window material 16 surrounds theinner diameter-forming mandrel 22 during the melting and deforming stepor steps, all forces on the mandrel 22 will be nearly in balance at alltimes. Any imbalance in the forces would be of such a low level thatonly a slight momentary bending could occur, which would not cause apermanent deformation of the mandrel 22. In some embodiments of theinvention, the plastic remains melted in the mold 28 for longer than ina conventional mold, so that even if there were to be some slightdeformation of the mandrel 22, the mandrel 22 would recover itsstraightness before cooling.

Where the methods of the invention are used to form a guidewire in whichthe optical assembly (comprising an optical fiber) is not required tomove within the window, the optical assembly may itself be used as themandrel, and be encapsulated within the window. In this case, there isno need to remove the mandrel at the end of the process. In this case aswell, it is preferred that the optical assembly not engage the distalmember so as to avoid damaging it mechanically or to avoid blocking thelight transmitting portions of the window. An interface is eliminated byencapsulating the optical assembly within the window in this way,reducing the interfaces at which indices of refraction need be matched.

It will be understood that methods of forming windows that are variantsof the methods described above are also within the scope of theinvention. For example, in some embodiments of the invention proximaltubular member 12 and/or a distal member 18 may have end sections whichform recesses with reduced inner diameter and the same outer diameter asmember 12 and/or 18, instead of forming steps with reduced outerdiameters as shown in FIGS. 1-4. In such case, it will be understoodthat window preform 16 may adhere to a proximal tubular member 12 and/ora distal member 18 by flowing into a recess in these members that isadapted to receive the window material, instead of flowing onto the stepportion to fill out the outer diameter as illustrated in FIGS. 1-4. Inaddition, methods and devices of the invention are further illustratedand explained in the Examples.

Where the methods of the invention are used to form a joint between twoobjects or materials, corresponding to a proximal tubular member and toa preform as illustrated in FIG. 1, there need be no membercorresponding to distal member. For example, a plastic part may bejoined with a tubular member by a method including the steps of placingan assembly at least partially within a mold, where the assemblyincludes a tubular member, a plastic preform comprising a material thatsoftens when heated, and a mandrel; softening the plastic preform (e.g.,by heating); and applying force effective to urge the tubular member andthe plastic preform together, effective to deform the plastic preformand to join it to the tubular member. The plastic preform may comprise amaterial selected from the group consisting of acrylic, polycarbonate,nylon, TEFLON® (polytetrafluorethylene), polyethylene terephthalate(PET), tensilized PET, resins, and blends thereof. Thus, the plasticpreform may comprise a combination of plastic materials, a resin that isat least partially uncured, a combination of resins at least some ofwhich are at least partially uncured, and other materials andcombinations of materials. The tubular member may be made of materialsincluding a metal, a ceramic, or other materials.

In the methods of joining a plastic part with a tubular member, theplastic preform may deform during softening or after it has beensoftened, and the step of applying force may occur during or followingthe softening of the plastic preform. In some embodiments of themethods, the assembly may be cooled. In some embodiments of the methods,the assembly may be removed from the mold; the removal of the assemblymay include a step including providing heat. In yet other embodiments,the methods include removing the mandrel from the assembly; the removalof the mandrel from the assembly may include a step including providingheat.

EXAMPLE 1

A borosilicate glass mold is prepared with a smooth circular innerdiameter of 0.014 inch.

A mandrel with an outer diameter of 0.0075 inch and a smoothly polishedend is placed through a hypotube guidewire body so that it protrudesfrom both ends of the hypotube guidewire body. The outer diameter of themandrel is sized to be the largest possible to allow free movementwithin the hypotube guidewire body. A piece of window tubing is placedover the end of the mandrel and moved up against the end of the hypotubeguidewire body. The volume of the window tubing is at least the volumeof the desired final window and window material parts. The outerdiameter of the window material is just less than 0.014 inch (as largeas possible while still less than the inner diameter of the mold).

The proximal end of the tip of the guidewire assembly is fitted over theprotruding end of the mandrel, and pushed towards the hypotube guidewirebody so that the window material is between and touching both thehypotube guidewire body and the proximal end of the tip of the guidewireassembly. The mold is slipped over these assembled parts, and the windowmaterial is centered inside the mold. While force is applied to bothends of the window material by urging the hypotube guidewire body andthe tip of the guidewire assembly towards the window material betweenthem, heat is applied to the mold effective to produce a temperaturesufficient to melt the window material but not the mold.

After allowing sufficient time for the window material to deform and toflow over the mechanical lock portions of the hypotube guidewire bodyand the tip of the guidewire assembly (the lock portions are illustratedin the figures as distal section 14 of proximal tubular member 12 andproximal section 20 of distal member 12), the heat is removed and theassembly is allowed to cool. The assembly is removed from the mold, andthen the mandrel is removed from the assembly. A quick, briefre-exposure to heat may be desired to facilitate removal of the assemblyfrom the mold or of the mandrel. After removal from the mold and removalof the mandrel, the formation of the window is complete.

EXAMPLE 2

Window assemblies have been produced with the following items, whereitem numbers relate to similar components illustrated in the Figures.Item 22 is a mandrel and item 12, a hypotube, is a proximal tubularmember. A hypotube is a tubular element useful in the manufacture of aguidewire, for example. Item 14 is a distal section of a proximaltubular member, that is, in this example, a distal portion of thehypotube. Item 16, a window preform, is an imaging window. Item 20, theproximal section of a distal member, is a proximal portion of aguidewire tip. Item 18, a distal member, is a guidewire tip. Item 28, amold, is a mold formed from borosilicate glass tubing. Item 40, a fiberoptic assembly 40, as illustrated in FIG. 4 above, fits within bore 38left by removal of mandrel 22. The following abbreviations are usedbelow: “OD” for outer diameter; “ID” for inner diameter; “NiTi” fornickel titanium alloy, or nitinol; “PET” for polyethylene terephthalate;“SS” for stainless steel; “DFT” for bis (p-fluorophenyl)-2,2,2trichloroethane; “VSS” for vanadium stainless steel; and “GRIN” forgraded index of refraction. As used in the Table below, “BMW design,”“S′ port design,” and “Balance design” refer to intravascular guidewiresthat are commercially available from Advanced Cardiovascular Systems,Inc. (Santa Clara, Calif.). Item Description Material and DimensionalInformation 22 Mandrel Teflon Coated Mandrel Parylene Coated Mandrel(Approximate Dimensions: OD: 0075″) 12 Hypotube NiTi/Chromium DopedHypotube Approximate Dimensions Overall Length: 40 cm OD: .0135″ ID:.0075 14 Distal Portion of Hypotube (Note: This was NiTi/Chromium DopedHypotube manufactured by plunge grinding the material) ApproximateDimensions OD: .0104″ Length: 7 mm 16 Imaging Window AcrylicPolycarbonate Nylon Tensilized PET Approximate Dimensions OD (i.e.profile) for all sections: .0135″ Section bonded to Item 3: [Length: 4mm] [ID: .0104″] Center Section: [ID: .0066] [Length: 3 mm] Sectionbonded to Item 5: [length: 4 mm] [ID: .0081″] 20 Proximal portion ofGuidewire tip Approximate Dimensions Max. OD of core wire: .0080″ 18Guidewire Tip Materials Used NiTi/SS DFT 304VSS NiTi ApproximateDimensions Max. OD of core wire: .0080″ Possible Designs 5 cm long BMWcore-to-tip design 7 cm long BMW design 5 cm long core-to-tip S'portdesign 7 cm long S'port design 5 cm long Balance design 7 cm longBalance design 28 Glass Tubing Material: Borosilicate OD: .070″ ID:.0139″ Length: 2″ 40 Fiberoptic Assembly Fiberoptic cable with thinpolyimide jacket (Single mode Fiber) with GRIN lens and Prisms/Mirrorattached. Approximate Dimensions Core OD: 8 microns Cladding OD: 125microns Polyimide Jacket OD: 140 microns Maximum OD: .055″

EXAMPLE 3

Windows comprising tensilized PET and polycarbonate were formed by themethod of this example. Window preforms were cut to length (1-10 mm)from tubes of tensilized PET and of polycarbonate. A drill was used tocreate a concave taper on both ends of the window preform. This taperhelps to center the proximal tubular member and the distal member. Whereonly one of the proximal tubular member and the distal member were to beattached, only one end of the window preform need be drilled to form ataper. A NiTi/Chromium Doped hypotube was used for the proximal tubularmember. The proximal tubular member was next inserted into and clampedin a motorized collet. The proximal tubular member was then rotated inthe collet and diameter of the end of the proximal tubular member wasreduced using a grinding stone to form a distal section suitable forreceiving the window preform. Next, a mandrel was inserted into the boreof the proximal tubular member, leaving sufficient length sticking outof the proximal tubular member to support the inner diameter of thewindow preform during assembly. A borosilicate glass tube mold was thenslid over the window preform. Under inspection with a microscope tocontrol the process, and with the proximal tubular member spinning, themold and the window preform were pressed into the spinning proximaltubular member. Alternatively, in cases where the mold is opaque, theincrease in force required to produce lateral motion of the windowpreform or proximal tubular member may be monitored to control theprocess. The friction from this process, including the spinning of theproximal tubular member and the pressure on the mold and window preformas they were pressed into the proximal tubular member, was sufficient tosoften tensilized PET and of polycarbonate window preforms for theformation of windows by this method. Following this last step, theassembly was removed from the collet. In order to attach a distal memberto the distal end of the window, the distal member may be inserted intothe collet and rotated, and the piece formed by these steps may beturned around, with the mold around the window, including the distal endof the window, so that the distal end of the window may be pressed intothe distal member.

EXAMPLE 4

This example illustrates the formation of a joint between a plasticpreform (termed a window preform in preceding examples) and a hypotubeaccording to a method of the invention. A borosilicate glass mold isprepared with a smooth circular inner diameter of 0.014 inch. The moldis configured to hold a hypotube and a plastic preform within its bore.

A mandrel with an outer diameter of 0.0075 inch and a smoothly polishedend is placed through a nickel titanium chromium-doped hypotubeguidewire body so that it protrudes from both the proximal and distalends of the hypotube guidewire body. The outer diameter of the mandrelis sized to be the largest possible to allow free movement within thehypotube guidewire body. A plastic preform comprising a tubular piece ofplastic to be joined to an end of the hypotube is placed over the end ofthe mandrel and moved up against the distal end of the hypotubeguidewire body. It will be understood that the plastic preform couldalso be a cylindrical piece of plastic placed in contact with themandrel. The outer diameter of the plastic preform material is just lessthan 0.014 inch (as large as possible while still less than the innerdiameter of the mold). The plastic preform comprises PET, although otherplastic materials are also suitable.

The plastic preform is pushed towards the hypotube guidewire body sothat the plastic preform material is touching the hypotube guidewirebody. The mold is slipped over these assembled parts. While force isapplied to both ends of the plastic preform material by urging thehypotube guidewire body and the plastic preform material together, heatis applied to the attachment side of the mold effective to produce atemperature sufficient to melt the plastic perform material but not themold. Such application of heat to the attachment side of the mold iseffective to reduce or prevent the application of heat to the distal endof the plastic preform opposite to the site of attachment to thehypotube. Alternatively, a distal portion of the plastic preform couldbe shielded from the heat.

After allowing sufficient time for the plastic preform material todeform and to flow over the mechanical lock portions of the hypotubeguidewire body (lock portions are illustrated in the figures as distalsection 14 of proximal tubular member 12), the heat is removed and theassembly is allowed to cool. The assembly is removed from the mold, andthen the mandrel is removed from the assembly. A quick, brief reexposureto heat may be desired to facilitate removal of the assembly from themold or of the mandrel. After removal from the mold and removal of themandrel, the joining of the plastic perform and the hypotube iscomplete. In this way a joint is formed between the plastic preform andthe hypotube. It will be understood that these methods are suitable forjoining many different materials.

While particular forms of the invention have been illustrated anddescribed, it will be apparent that various modifications can be madewithout departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited except asby the appended claims.

1. An intracorporeal device, comprising: a proximal portion; a distalportion disposed at an end of the proximal portion; and a window securedto and between said proximal and distal portions, said window and saidproximal and distal portions being formed of materials having melttemperatures, said window material having a melt temperature below thatof the melt temperatures of said proximal and distal portions.
 2. Theintracorporeal device of claim 1, wherein said window directly contactsand is secured to said proximal and distal portions.
 3. Theintracorporeal device of claim 1, wherein said window includes a smoothtube that is at least one of translucent and transparent to enabletransmission of light without excessive attenuation.
 4. Theintracorporeal device of claim 1, wherein said window has an index ofrefraction between about 1.3 to 1.4.
 5. The intracorporeal device ofclaim 1, wherein said window transmits optical radiation having awavelength of about 0.75 micron to 2.5 micron.
 6. The intracorporealdevice of claim 1, wherein said window is not extruded and press fit tosaid proximal and distal portions.
 7. An intracorporeal device having asubstantially cylindrical window, comprising: a molded assemblyincluding a proximal tubular member, a distal member, a window performhaving a material that may soften, said window preform being disposedbetween said proximal tubular member and said distal member; whereinsaid window perform is soft and deformed under pressure; and whereinsaid proximal tubular member and said distal member are urged togetherto deform said window preform to form a window:
 8. The intracorporealdevice of claim 7, wherein the window preform comprises a polymericmaterial.
 9. The intracorporeal device of claim 7, wherein the windowpreform comprises a combination of polymeric materials.
 10. Theintracorporeal device of claim 7, wherein the window preform comprises aresin that is at least partially uncured.
 11. The intracorporeal deviceof claim 7, wherein the window preform comprises a combination of resinsat least some of which are at least partially uncured.
 12. Theintracorporeal device of claim 7, where the window preform comprises amaterial selected from the group consisting of acrylic, polycarbonate,nylon, polytetrafluoroethylene (TEFLON®), polyethylene terephthalate(PET), tensilized PET, resins, and blends thereof.
 13. Theintracorporeal device of claim 7, wherein the window preform has alength of between about 1 mm and about 11 mm.
 14. An intracorporealdevice having a substantially annular window, comprising: a moldedassembly including a proximal tubular member, a distal member, a tubularwindow preform having a material that softens when illuminated, saidwindow preform being disposed between said proximal tubular member andsaid distal member; and wherein said proximal tubular member and saiddistal member are urged together to deform said window preform to form awindow for transmission of light.
 15. The intracorporeal device of claim14, wherein said device further comprises a mandrel passing through saidproximal tubular member and into the tubular window preform.
 16. Theintracorporeal device of claim 15, wherein said mandrel includes a fiberoptic filament.
 17. The intracorporeal device of claim 15, wherein saidmandrel includes a fiber optic filament, a mirror, and a lens.
 18. Theintracorporeal device of claim 14, wherein said material is selected sothat it softens when illuminated by a light selected from the groupconsisting of ultraviolet light, visible light, and infrared light. 19.The intracorporeal device of claim 14, wherein an outer surface formedby said proximal tubular, said tubular window, and said distal member issmooth and continuous.